Question 33 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is A **Explanation for Option A (Correct):** The primary and most effective method specifically engineered into a vessel's sea water cooling system to clear ice buildup within a sea chest during operation in icy waters is the application of heat. The "steaming out sea chest blow connection" allows high-pressure steam (usually supplied from the ship's auxiliary steam line) to be injected directly into the sea chest. This steam rapidly melts the accumulated ice and ensures the continued flow of cooling water, preventing system failure. This provision is standard practice on ships designed to operate in regions prone to ice formation. **Explanation for Other Options (Incorrect):** * **B) The ice may be removed by using the chemical de-icing antifreeze connection, if provided.** While some specialized systems might utilize chemical inhibitors or antifreeze (especially for smaller, critical lines), injecting large quantities of chemical de-icing agents into the main sea chest is generally avoided for several reasons: it is expensive, environmentally problematic (polluting the seawater), and less universally effective than steam for rapidly clearing a large, obstructed sea chest volume. This connection type is not the standard primary provision for this task. * **C) The ice may be removed by using the compressed air sea chest blow connection, if provided.** Compressed air connections (often used for routine blowing down or clearing minor debris/silt) are ineffective for removing solid, frozen ice. Injecting air might bubble the water but will not melt the ice; it might even make the problem worse by chilling the structure further through adiabatic expansion. * **D) The ice may be removed by using the fire main flushing connection, if provided.** The fire main flushing connection provides ambient or slightly pressurized cold seawater. Using cold water to flush a sea chest full of ice would be counterproductive, as it would introduce more cold water, potentially exacerbating the freezing problem rather than solving it. Heat (steam) is required for de-icing.